The Key Technologies Of High-speed Burst-mode Optical Receiver

Nowadays burst mode datas are more and more transmitted in optical fiber communication system. In optical fiber backbone networks optical burst switching (OBS) is considered to be an effective technique in the next generation Internet, for the advantage of the integration of both circuit switching and packet switching. As the different distance between source router and terminal in OBS networks, the difference of amplitude and phase of each burst packet is very large, so a burst mode optical receiver is needed to recover the signals.One of the most potent and effective techniques in optical fiber access networks is the passive optical network(PON), the key factors of which in physics layer transmission are upstream data in burst mode and downstream data in broadcasting mode. For the influence on velocity and bandwidth, the reception for upstream data in burst mode is more worthy of note.Some key issues on burst mode optical reception are studied here especially on the signal reshaping. In order to solve the problem, AC-coupled receiver is designed, which is simulated at the bit rate up to 2.5Gb/s. Summarizing the process of design,each part of the receiver is finished well, including APD modeling, preamplifier with automatic gain control, alterable time constant circuit, limiting amplifier and noise eliminating circuit. Additionally, a DC-coupled receiver is also presented based on AC-coupled circuit.Some schemes are presented here to improve the functions of burst mode optical receiver, which are as follows: First, an internal feedback is used to keep preamplifier stable, and an active inductance to broaden band; Second, meliorating the ordinary AC-coupled circuit with a few voltage controlled switches, which the time constant can be alternated, and consequently both the preamble time and the guard time are decreased; Third, with"AND"twice the remaining noise is eliminated; Fourth, a new frame is presented for optical burst to avoid bit error, which contains frame-end in the end of the burst.. The performance of the two coupled-style receivers is also presented here with at the bit rate up to 2.5Gb/s respectively. For AC-coupled receiver the sensitivity is -34.6dBm, the dynamic range is 34.4dB, the preamble time is 3.2ns and the guard time is 16ns. For DC-coupled receiver the four factors mentioned above is -35.2dBm, 35.0dB, 45.2ns and 7.2ns respectively. Compared with other AC-coupled receivers designed before, the performance of the one presented here is better than ever before.Additionally, a discussion about the performance caused by preamble time and guard time is also presented in the last chapter, which includes bit error rate, signal-to-noise ratio and channel utilization. The results simulated by MATLAB shows that BER and SNR will be ameliorated by increasing the preamble time and guard time, however, network capacity will be deteriorated meanwhile.